Aircraft seats comprising adjustable seat elements, such as backrests, arm rests, leg rests or seat surfaces are generally known. The adjustment is a relative change in the position and/or orientation of two or more seat elements. This can include, for example, setting the angle of a backrest relative to a seat surface or adjusting the height of the leg rest relative to the seat surface. A seat element can be adjusted relative to a further seat element by means of rotation about an axis, by means of displacement along an axis, or by means of adjustment along a trajectory. Moreover, seat elements, in particular the seat surface, are adjusted relative to a seat base or a seat frame which is fixed to the cabin floor.
The adjustment of seat elements is made possible by means of adjusting devices, which allow two or more seat elements of an aircraft seat to move relative to one another within specified limits.
Aircraft seats providing a normal level of comfort, which are provided for as dense a seat arrangement as possible in an aircraft, usually comprise mechanical adjusting devices for seat elements, which a seat occupant can release from a locked position by means of an operating lever or operating button. The operating lever is connected to the adjusting device and to a corresponding locking element by means of cables, rods or hydraulic lines for mechanical transmission of the unlocking force.
The mechanical transmission of the unlocking force in order to allow a corresponding force transmission from the operating lever to the adjusting device has a complex configuration on account of the distance to be bridged between an operating lever, e.g. at the end of an armrest, and an adjusting device, e.g. on the joint between the seat surface and the backrest. Moreover, possible transitions between seat elements and changes of direction in the case of force transmission in small radii, e.g. at the transition from an armrest to a backrest, must be bridged. Transitions of this kind can in addition be in the form of a joint, as a result of which the mechanical force transmission must occur in an equally complex articulated manner and occupies a correspondingly large amount of space, considerably limiting the design freedom of the aircraft seats. Moreover, mechanisms of this kind can be subject to considerable friction, meaning that they are difficult for an operator to operate, in particular after a long service life. Bowden cables or hydraulic systems, for example, can be used for the purpose of mechanical force transmission.
In contrast, aircraft seats exist which comprise electrically driven adjusting devices. Said devices make it possible for seat elements to be adjusted by means of actuating drives. The actuating drives are electronically activated and can be controlled by a seat occupant by means of control keys. In this way, the angle of a backrest to a seat surface can be adjusted or changed electrically for example. The actuating drives are designed such that one or more seat elements can also be adjusted against the weight of a seat occupant. Moreover, the actuating drives must be designed in such a way that they are able to safely withstand the loads which occur in the event of a crash. On account of these requirements, the servomotors are heavy and also expensive. In addition, the necessary size of the servomotors limits the design freedom of an aircraft seat during integration. If a plurality of adjustable seat elements are provided on an aircraft seat, it must be laboriously ensured that no combination of positions of the seat elements can be reached which could trap or injure a seat occupant.
The object of the invention is to provide an adjusting device for an aircraft seat which overcomes the above-mentioned disadvantages.